17.1.3. Past and Present Trends

The Intergovernmental Panel on Climate Change (IPCC) in its Second Assessment
Report (SAR) projected a global average temperature increase of 1.0-3.5°C,
and a consequential rise in global mean sea level of 15-95 cm by the year
2100. Results from observational data show that temperatures have been increasing
by as much as 0.1°C per decade and sea levels by approximately 2 mm yr-1
in the regions where most of the small island states are locatednamely,
the Pacific, Indian, and Atlantic Oceans and the Caribbean Sea (see Figure
17-1). There also is evidence that the ENSO phenomenon will continue
to have a major influence on climate variability in these regions.

Figure 17-1: Main regions of the world in which small island states
are located.

Analyses conducted by the New Zealand Meteorological Services
reveal that, since 1920, temperature has risen by 0.6-0.7°C in Noumea
(New Caledonia) and Rarotonga (Cook Islands), which is greater than the mean
global increase. Based on data from 34 stations in the Pacific from about 160°E
and mostly south of the equator, surface air temperatures have increased by
0.3-0.8°C during the 20th century, with the greatest increase in the
zone southwest of the SPCZ. This is well in excess of global rates of warming.
Further recent work undertaken by the New Zealand Institute of Water and Atmospheric
Research (NIWA) shows a noticeable change in aspects of the South Pacific climate
since the mid-1970s. For instance, western Kiribati, the northern Cook Islands,
Tokelau, and northern French Polynesia have become wetter, whereas New Caledonia,
Fiji, and Tonga have become drier. Meanwhile, Samoa, eastern Kiribati, Tokelau,
and northeast French Polynesia have become cloudier, with warmer nighttime temperatures;
New Caledonia, Fiji, Tonga, the southern Cook islands, and southwest French
Polynesia and Tuvalu have become warmer and sunnier (Salinger et al.,
1995). It also might be noted that in the Pacific generally, observed changes
in temperature and cloudiness appear to be closely influenced by the pattern
of ENSO events (Salinger, 1999).

The records also indicate that rainfall has increased in the northeast Pacific
but has decreased in the southwest Pacific region. Interannual variations in
temperature and rainfall are strongly associated with ENSO, resulting in water
shortages and drought in Papua New Guinea, the Marshall Islands, the Federated
States of Micronesia, American Samoa, Samoa, and Fiji. Although a causal link
has yet to be established, all of the foregoing changes have coincided with
an eastward shift of the SPCZ since 1970. Research now suggests that some of
the foregoing changes (including the shift in the SPCZ) may be closely correlated
with interdecadal patterns of variabilityfor example, the Pacific Decadal
Oscillation (PDO) (Salinger and Mullen, 1999). It should be noted, nevertheless,
that the changes observed in the 20th century are considered to be consistent
with patterns related to anthropogenic GHG-induced climate change (Salinger
et al., 1995; Hay, 2000).

The most significant and more immediate consequences for small island states
are likely to be related to changes in sea levels, rainfall regimes, soil moisture
budgets, and prevailing winds (speed and direction), as well as short-term variations
in regional and local sea levels and patterns of wave action (Sem et al.,
1996). The short-term (including interannual) variations are likely to be strengthened
by the ENSO phenomenon. Vulnerability assessment studies undertaken in some
small islands suggest that climate change will impose diverse and significant
impacts on small island states (Leatherman, 1997). In most small islands (including
the high islands), the majority of the population, socioeconomic activities,
and infrastructure are located within a few hundred meters of the coast; therefore,
they are highly vulnerable to the impacts of climate change and sea-level rise
(Hay et al., 1995; Bijlsma, 1996; Nurse et al., 1998; Burns, 2000).
In this regard, an increase in the frequency and magnitude of tropical cyclones
would be a major concern for small island states. This would increase the risk
of flooding, accelerate existing rates of beach erosion, and cause displacement
of settlements and infrastructure.

The key questions, therefore, are how will the impacts manifest themselves,
and what are the most appropriate responses for avoiding, minimizing, or adapting
to these impacts? Because small island states traditionally experience some
of the greatest interannual variations in climatic and oceanic conditions, many
of their natural systems are well adapted to the stresses that result. Thus,
many strategies that small island states might employ to adapt to climate change
usually are the same as those that constitute sound environmental management,
wise use of resources, and appropriate responses to present-day climate variability.

Although the full extent of climate change impacts in the small island states
is far from certain, mostly adverse consequences are projected for several systems.
The combined effect of GHG-induced climate change and sea-level rise can contribute
to coastal erosion and land loss, flooding, soil salinization, and intrusion
of saltwater into groundwater aquifers. The quantity and quality of available
water supplies can affect agricultural production and human health. Similarly,
changes in SST, ocean circulation, and upwelling could affect marine organisms
such as corals, seagrasses, and fish stocks. Tourismwhich is a very important
economic activity in many island statescould be affected through beach
erosion, loss of land, and degraded reef ecosystems, as well as changes in seasonal
patterns of rainfall.